Infrared (ir) communication device for motor vehicles

ABSTRACT

A motor vehicle infrared (IR) communication device ( 2 ) for an electronic fee-charging system, comprising IR transmitting and receiving elements ( 9 ) arranged in a housing ( 4 ) and oriented according to a first direction ( 10 ), which first direction ( 10 ) extends at least substantially in a vertical longitudinal plane of the motor vehicle when the communication device ( 2 ) is in a state installed in a motor vehicle, and transmitting and receiving electronics ( 36, 37 ); further IR elements ( 13 ) oriented at least according to a second direction ( 14 ) are additionally arranged in the housing ( 4 ), this second direction ( 14 ) being oriented towards a side, relative to the first direction ( 10 ), or to the vertical longitudinal plane, respectively.

The invention relates to an infrared (IR) communication device for motorvehicles, preferably for an electronic fee charging system, comprisingIR transmitting and receiving elements arranged in a housing andoriented according to a first direction, which first direction extendsat least substantially in a vertical longitudinal plane of the motorvehicle when the communication device is in a state installed in a motorvehicle, and transmitting and receiving electronics.

Such infrared-based communication devices for motor vehicles, alsocalled “on board units” (OBU in short), are used for electronic tollingsystems or also for charging fees in parking places etc., for electronicfee charging systems in general, these OBUs being provided forcooperating with stationary communication devices at the respectivetraffic area, e.g. in the form of beacons on freeways. Suchcommunication devices or fee charging systems are known from WO01/59711, e.g. From EP 625 767 A, it is furthermore also known to checkmotor vehicles equipped with such communication devices from movingchecking vehicles (so-called “mobile enforcement”) as regards the properdebiting of fees, which debiting is effected via the OBU. In this caseit is necessary for the checking vehicle to pass the checked vehicle andto take its place in front of the latter in order to then start throughthe rear window the IR communication with the checked vehicle and toinquire from this vehicle fee data or a recorded debitings,respectively. If it is found out that no debiting has been recorded orthat possibly the checked vehicle lacks an OBU, the checked vehicle canbe recorded or stopped immediately so as to record respective vehicleand driver's data.

One problem is, however, that often it will not be possible to takeone's place in front of a vehicle to be checked, so that the so-called“mobile enforcement” described will then not be feasible. On the otherhand, the communication devices as a rule are adapted for shortdistances only, e.g. from 5 to 10 m, wherein the angle of radiation andthe receiving angle, or generally, the directional characteristic of thetransmitting and receiving elements, is relatively narrow so that thedescribed check cannot be carried out in any other way than afterpassing the vehicle to be checked.

Moreover, since the transmitting and receiving elements of thecommunication device described are oriented in the driving direction,they cannot be utilized for other purposes, whereas it would often bedesirable to allow also for a different communication with therespective vehicle.

It is now an object of the invention to solve these problems and todesign the initially described communication device in such a way thatother communication possibilities are rendered possible, particularlythat also a basis for a mobile enforcement by a checking motor vehicleis efficiently achieved.

To solve this problem, the invention provides for a communication devicecomprising the features set out in claim 1. Advantageous embodiments andfurther developments are defined in the sub-claims.

In the communication device according to the invention, it is providedthat in addition to a communication in the driving direction, aselective communication is rendered possible also in lateral direction,and this lateral communication may be used for various purposes, inparticular for a mobile enforcement by means of checking vehiclespassing the vehicle to be checked, but also for a communication e.g.with motor vehicles moving in the opposite direction, for transmittingimportant traffic information (e.g. to caution them about a traffic jamor a fog zone). This communication in the second direction, the “lateraldirection”, may be provided such that only on one side of the motorvehicle this further, selective communication is rendered possible, inparticular obliquely towards the left front side as seen by the driverin case of right-hand traffic, yet obliquely towards the right frontside in case of left-hand traffic. Optionally, this communication can beinstalled both towards the left and also towards the right, as viewed bythe driver of the motor vehicle, and the radiation angles, moreover, canvary within a relatively wide range. With a view to a sufficiently longperiod of time during which the transmitting and receiving lobes of twovehicles moving in opposite directions will overlap, an obliqueorientation is to be preferred over a communication oriented under 90°relative to the driving direction.

It has proved to be particularly suitable if as further IR elementsoriented in the second direction, only IR transmitting elements areprovided and if for the IR receiving elements oriented in the firstdirection, a directional characteristic which is sufficiently wide alsofor receiving in the lateral direction is provided. Since the IRtransmitting elements require relatively much electric energy incomparison with receiving elements, an energy-efficient, selectivecommunication will be ensured in this manner by means of a few infraredtransmitting elements, while on the other hand, due to the narrowdirectional characteristics of the respective transmitting elements,also the selectivity of the communication in both directions will not beadversely affected when mutually shared IR receiving elements having acorrespondingly wider directional characteristic are employed for thecommunication in the driving direction as well as in the lateraldirection. In this case it has also been shown to be suitable if thedirectional characteristic of the IR receiving elements oriented in thefirst direction has a half value angle of from ±50° to ±75°, preferablyapproximately ±60°.

For the lateral communication, in particular for an exchange ofinformation with oncoming vehicles, ideally a directional characteristicwould have to be sought which has the shape of a parallelogram seen intop view, so as to ensure approximately constant lengths of paths forthe communication of the two vehicles in the driving direction and inthe counter-driving direction. Such a directional characteristic canvery well be approximated in a simple manner in that the IR elementsoriented in the second direction partly comprise a first, narrower farfield directional characteristic and for at least one other partcomprise a second, wider near field directional characteristicoverlapping the first directional characteristic. In this respect it isfurthermore advantageously provided that the at least two overlappingdirectional characteristics overlap each other in a pre-determinedmixing ratio, e.g. of approximately 2:1, the mixing ratio beingdetermined by the respective number of IR elements and/or by thepre-determined amount of the current flowing therethrough. Here,preferably, the narrower far field directional characteristic has ahalf-value angle of approximately ±10°, whereas the wider near fielddirectional characteristic preferably has a half-value angle ofapproximately ±20°.

As has already been mentioned, preferably an oblique orientation is tobe provided for the second direction, and it has proved to beparticularly advantageous if the second direction encloses an azimuthangle with the vertical longitudinal plane of from 35° to 55°,preferably approximately 45°. As has already been mentioned, preferablyone and the same IR receiving elements are used for the communication inthe direction straight ahead as well as in the lateral direction. If thepresent communication device then is merely used in electronic tollingor fee charging systems, e.g., wherein optionally also a check by alaterally passing or overtaking motor vehicle is rendered possible, thetwo communications may simply merge in one and the same receivingelectronics and the data processing means connected thereto. If,however, a communication with other vehicles shall be rendered possiblefor an exchange of, e.g., traffic information, provisions must be takenin view of the mutually shared receiving elements and receivingelectronics that the information or data received will be separatelyfurther processed according to type, and in a further development of theinvention it is therefore preferably provided that a data discriminatordetecting the type of received data is connected to the receivingelectronics, to which different data processing circuits are connectedto which the respective data are supplied in dependence on the data typedetection. Since, furthermore, only a short period of time in the orderof from one to three tenths of a second is available for such aninformation exchange between vehicles which meet, and, moreover, specialefforts must not be required for the transmission of information whichwould require the driver's concentration, it is suitable to storecertain information beforehand and to retrieve it by means of codes.Then it will preferably be further provided that a memory forpre-determined messages is associated to a data processing circuit andthat data transmitted in the second direction, or received from thesecond direction, respectively, and supplied by the receivingelectronics to the data processing circuit comprise address informationfor reading out the respective messages from the memory. The messagesread out of the memory may then be optically reproduced on a display, orthey may be reproduced acoustically.

As also has already been mentioned before, the communication deviceaccording to the invention may advantageously also be employed for acheck by mobile checking units, i.e. motorized checking vehicles, andfor this instance, it is particularly provided that a data processingcircuit is associated to a fee charging unit as well as connected to thetransmission electronics for returning data relating to fees charged inthe second direction.

In the following, the invention will be explained in more detail by wayof preferred exemplary embodiments, to which, however, it shall not berestricted.

FIG. 1 shows a schematic, partially sectioned perspective view of aninfrared communication device which is mounted on a partiallyillustrated windshield of a motor vehicle, wherein schematically and nottrue to scale also a transmission lobe for a lateral communication aswell as a transmission and receiving lobe for a communication in drivingdirection are entered on a reduced scale;

FIG. 2 shows a top view onto this communication device, withoutwindshield, a side lobe for the communication in the second, lateraldirection being illustrated;

FIG. 3 schematically shows an IR transmitting element on a chip with theassociated transmission lobe, or directional characteristic,respectively;

FIG. 4 shows a directional characteristic composed of two transmissionlobes of two IR transmitting elements or two groups of transmittingelements, i.e. with a near field directional characteristic and with anarrower far field directional characteristic;

FIG. 5 in a quite schematic top view shows the use of a communicationdevice according to the invention for the purpose of a check by apassing checking motor vehicle;

FIG. 6 in partial FIGS. 6A and 6B shows associated block diagrams forthe transmitting and receiving devices in the checked vehicle (FIG. 6A)as well as in the checking vehicle (FIG. 6B);

FIG. 7, in a schematic top view comparable to FIG. 5, shows a motorvehicle with a communication device according to the invention for acommunication in the second, lateral direction with a vehicle moving inthe opposite direction which is merely indicated by an arrow, with adirectional characteristic comparable to that according to FIG. 4; and

FIG. 8 shows a block diagram of a communication device according to theinvention, which is adapted both for the usual exchange of feeinformation and for debiting fees and also for a data exchange withoncoming vehicles.

According to FIG. 1, an infrared (IR) communication device 2 in the formof a so-called “on board unit” (in the following called OBU in short) isattached by means of a mounting base 3 to a windshield 1 of a vehiclenot further illustrated. The OBU 2 has a housing 4 in the interior ofwhich the required electronic circuit 5 is arranged which, however, isnot further illustrated in FIG. 1—and, likewise, neither in FIG. 2—andwhich may be designed in a per se conventional manner. According to theillustrations in FIG. 1 and also in FIG. 2, the driving direction istowards the left, cf. also the respective arrows 6.

In the housing 4, behind transparent windows 7 and 8, respectively,arrays of IR elements are provided, i.e., in detail, on the broadside ofthe device 2 facing forwards, an array 9 of IR transmitting andreceiving elements, cf. FIG. 2, which are oriented in a first direction10 as regards radiation and reception; this first direction 10 (cf.particularly FIG. 1) extends obliquely upwards, under an inclination ofe.g. approximately 45° or 55° relative to the horizontal line, and in avertical plane parallel to the driving direction 6 or also to thelongitudinal axis of the motor vehicle not further illustrated. In thisfirst direction 10, the IR transmitting and receiving elements each havea relatively wide directional characteristic 11, both in verticaldirection (FIG. 1) and also in horizontal direction (FIG. 2), e.g. witha respective half-value angle of ±60°.

The second array of IR elements 13 is located laterally in the housing 4of OBU 2, these elements preferably being mere IR transmitting elementswhich are oriented in a second direction 14 obliquely forwards andtowards the side, relative to the driving direction 6. As is visiblefrom FIG. 1, this second direction 14 preferably extends approximatelyhorizontally, if the associated motor vehicle is standing or moving on aplane traffic surface. The angle which the second direction 14 encloseswith the first direction 10, seen in top view (cf. FIG. 2), or with avertical plane laid through the first direction 10, in the drivingdirection 6, amounts to approximately 45°, e.g. In FIGS. 1 and 2,moreover, the narrower directional characteristic 15 associated withthese laterally oriented IR transmitting elements 13 is shown, thisdirectional characteristic 15, as will be explained in more detail byway of FIG. 4 hereinafter, preferably being composed of two transmittinglobes or directional characteristics by the array of IR transmittingelements 13 being realized by two groups of IR transmitting elements,one group of which defining a narrower far field directionalcharacteristic and the other one defining a near field directionalcharacteristic which, compared to the former one, is somewhat wider.

In FIG. 3, an IR transmitting element 16 having the form of alight-emitting diode (LED) 16 is shown, a transparent plastics housing19 being mounted on a chip (i.e. an integrated circuit) 17 thatcomprises the light-emitting diode proper and which is provided withterminals 18, the plastics housing 19 acting as a lens and having adiameter of from 3 mm to 5 mm, e.g. Depending on the distance of thechip 17 from the focus of the lens defined by the housing 19, differenttransmission lobes 20 will result having defined half-value angles α.According to FIG. 3, the half-value angle α of the transmission lobe ordirectional characteristic 20 will be approximately ±20°, e.g. Now, ifas suggested before, the IR transmitting elements 16 are overlappingwith different transmission lobes 20, having different half-value anglesα and different ranges, a combined directional characteristic 15approximately of the form as shown in FIG. 4 may be obtained with whichan approximately parallelogram-type shape (cf. FIG. 7) as regards thelength of path in the driving direction can be obtained.

In detail, according to FIG. 4—and not true to scale—a narrower farfield directional characteristic 21 overlaps a wider near fielddirectional characteristic 22 so as to obtain the combined directionalcharacteristic 15. The half-value angle for the two directionalcharacteristics 21, 22 are, e.g., approximately ±10° and approximately±20°, respectively. To generate the far field and the near field,respectively, a certain mixing ratio is required which can be adjustedby the respective number of diodes, i.e. IR transmitting elements 13,and/or by the circuit-determined transmission current through thediodes, as is known per se and need not be further explained here. Inthis way, two approximately equal, constant communication paths S1 andS2 (cf. FIG. 7) can be obtained by means of the combined directionalcharacteristic 15.

In FIG. 5, a two-lane roadway 23 is quite schematically shown in a topview, and this roadway is equipped with a conventional stationaryoverhead toll unit 24 comprising stationary communication devices 25, 26for a selective communication with vehicles 27, 28 moving in the lanes.These stationary communication devices, 25, e.g., will communicate indetail selectively with the respective OBU 2, e.g. in vehicle 28, fordebiting tolls, with those IR transmitting and receiving elements 9 ofOBU 2 here being in operation which are oriented in the first direction10, corresponding to a vertical plane through the driving direction 6.This data exchange between stationary and mobile communication devicefor the purpose of electronic toll collection is known per se and neednot be further explained here.

From FIG. 5 it may furthermore be seen that on at least one side of thevehicle 28, i.e. obliquely towards the front, in the second direction14, a transmission lobe 15 is given which is determined by the OBU 2 or,more precisely, by the second IR transmission element 13 of the latter,to thus communicate with a passing checking vehicle 29 which contains acomparable communication device 30 which is oriented under anappropriate angle, e.g. 135° relative to the driving direction 6′ asregards transmission and receiving characteristics, cf. the directionalcharacteristic 31 having a half-value angle of approximately ±25° inFIG. 5. In this manner, the checking vehicle 29 can inquire in the OBU 2of the checked vehicle 28 data regarding the recorded debitings orpayments of tolls as well as data regarding the owner of the vehicle.This may be effected in a simple manner by driving side by side orduring the passing procedure, and it is not necessary for the checkingvehicle 29 to get into the position directly in front of the checkedvehicle 28 after having changed lanes.

In FIG. 6, this data exchange between the vehicles 28 and 29 isschematically illustrated by showing block diagrams of the respectivecommunication devices 2 (FIG. 6A) and 30 (FIG. 6B). The OBU 2 of thechecked vehicle 28 contains, e.g., a microprocessor 32 in a per seconventional manner (cf. FIG. 6A), which has an associated memory 33 aswell as a “fee card” 34, and which controls two separate transmissionelectronics components 36.1 (for transmission in the first direction 10,by means of the first IR transmitting elements in array 9), as well assecond transmission electronics 36.2 (for transmitting in the seconddirection 14, by means of the IR transmitting elements 13 of the secondarray). For a communication in both directions 10, 14, the mutuallyshared IR receiving elements in the first array 9 are employed, and theoutput signals thereof are processed in an amplifying and pulse-formingstage 37 for an application to the microprocessor 32.

In a comparable manner, in the communication device 30 of the checkingvehicle 29 (cf. FIG. 6B), a microprocessor 38 is contained as a centralcontrolling and data processing component, to which the IR signalsreceived via IR receiving diodes or, generally, IR receiving elements 39are supplied after an appropriate amplification and pulse formation inan amplifier and pulse forming component 40. The microprocessor 38furthermore has an associated controlling and inputting unit 41 as wellas a memory 42. Moreover, it is visible in FIG. 6B that with anappropriate input via the inputting unit 41, the microprocessor 38controls IR transmitting elements having the form of LEDs 43 viaassociated transmitting electronics 44. In a checking procedure, this isdone initially so as to “wake up” OBU 2 in the checked vehicle 28 andthen question it, i.e. invite it to transmit pre-determined recordedbooked data. These booked data will then be read out by themicroprocessor 38 in OBU 2 from the memory 32 and transmitted via thetransmission electronics 36.2 and the IR transmitting elements 13 aswell as received by the communication device 30 via its receivingelements 43.

In FIG. 7, a further possible application of the present communicationdevice 2 is schematically illustrated. Again, a motor vehicle 28′equipped with such a communication device, or OBU 2, respectively, movesin a driving direction 6, e.g., in the right-hand lane of a roadway 23of a freeway. On the counter-direction roadway 23′, e.g. a vehicle 48indicated merely by an arrow moves, i.e. in the opposite lane, also inthe right lane thereof. In FIG. 7, also the combined directionalcharacteristic 15 for vehicle 28′ is schematically illustrated (cf. theprevious discussion regarding FIG. 4), it being visible thatapproximately constant lengths of paths S1, S2 are covered by thecombined directional characteristic 15 for the two vehicles 28′ and 48so as to adequately accomplish the communication in the drivingdirection and the counter driving direction, respectively. This alsoapplies if the two vehicles 28′, 48 each move in the respectiveleft-hand lane.

In FIG. 8, corresponding to FIG. 6A, the microprocessor 32 including theRAM memory 33 connected thereto as well as the transmission andreceiving electronics 36.1, 36.2 and 37 (cf. also FIG. 7) areillustrated as components for OBU 2. They have associated IR elementarrays 9 and 13, respectively, which are oriented in the first direction10 and in the second direction 14, respectively, cf. the correspondingtransmission and receiving lobes 11 in the first direction 10 and thetransmission lobe 15 in the second direction 14, respectively. Thereceiving lobe 11 is adapted to be able to receive also signals comingfrom the direction which is contrary to the second direction 14, i.e.the corresponding IR receiving elements of the first array 9 areprovided with an appropriately wide directional characteristic.

If used also for an exchange of information other than for fee chargingpurposes, as indicated in FIG. 7, the signals or data received via theIR receiving elements 9 and the receiving electronics 37 must bedistinguished and separated, which can be carried out at microprocessor32 simply on the basis of the type of data supplied—the microprocessor32 thus also forms a data discriminator 32′ so as to transmit thereceived data depending on their type either to a first data processingcircuit 49 for the fee module merely schematically shown in FIG. 8 by ablock 50, or to supply the data received at an exchange of informationwith the oncoming vehicle 48 to a second data processing circuit 51which supplies appropriate messages to a reproduction unit 52.Preferably, a certain number of pre-defined messages, such as “Fogahead”, “Accident ahead” or “Traffic jam ahead” etc. are kept stored ina memory 53, the received data containing address information forretrieving the respective messages from the memory 53 to be reproducedvia the reproduction unit 52. The reproduction unit 52 may simply be adisplay, i.e. an optic reproduction unit, yet thereinstead or inaddition thereto also an acoustic reproduction unit may be provided, inwhich case the messages stored in memory 53 will contain appropriate(additional) voice information.

For the sake of completeness, in FIG. 8 also a program memory 54 for themicroprocessor 32 is illustrated.

When in FIG. 7 the second direction 14 is illustrated to extendobliquely towards the left front side, this is not to be considered asrestrictive, since in countries with left-hand traffic an invertedmirror-type arrangement with the second direction 14 extending obliquelylaterally towards the right instead of towards the left, would have tobe provided. In particular, the communication device 2 may right fromthe start be provided with a middle array 9 of infrared transmitting andreceiving elements as well as with two lateral IR elements 13, namelyfor a lateral radiation towards the left, and for a lateral radiationtowards the right. Depending on the respective country in which thecommunication device, or OBU 2, respectively, will then be mounted,either one or the other lateral IR element group 13 can be activated.

1-12. (canceled)
 13. A motor vehicle infrared (IR) communication device(2), preferably for an electronic fee-charging system, comprising IRtransmitting and receiving elements (9) arranged in a housing (4) andoriented according to a first direction (10), which first directionextends at least substantially in the travel direction of the motorvehicle when the communication device (2) is in a state installed in amotor vehicle, and comprising further IR elements (13) additionallyarranged in the housing (4) and oriented at least according to a seconddirection (14), this second direction (14) being oriented towards oneside, relative to the first direction (10), and transmitting andreceiving electronics (36, 37), wherein, as further IR elements (13)oriented in the second direction (14), only IR transmitting elements areprovided, and in that for the IR receiving elements (9) oriented in thefirst direction (10), a directional characteristic (11) which issufficiently broad also for receiving in the lateral direction isprovided.
 14. A communication device according to claim 13, wherein thedirectional characteristic (11) of the IR receiving elements (9)oriented in the first direction has a half value angle of from ±50° to±75°, preferably approximately ±60°.
 15. A communication deviceaccording to claim 13, wherein the IR elements (13) oriented in thesecond direction (14) partly comprise a first, narrower far fielddirectional characteristic (21) and for at least one other part comprisea second, wider near field directional characteristic (22) overlappingthe first directional characteristic.
 16. A communication deviceaccording to claim 15, wherein the at least two overlapping directionalcharacteristics (21, 22) overlap each other in a pre-determined mixingratio, e.g. of approximately 2:1, the mixing ratio being determined bythe respective number of IR elements (13) and/or the pre-determinedamount of the current flowing therethrough.
 17. A communication deviceaccording to claim 15, wherein the narrower far field directionalcharacteristic (21) has a half-value angle of approximately ±10°.
 18. Acommunication device according to claim 15, wherein the wider near fielddirectional characteristic (22) has a half-value angle of approximately±20°.
 19. A communication device according to claim 13, wherein thesecond direction (14) defines an azimuth angle with the first direction,seen in top view, of from 35° to 55° preferably approximately 45°.
 20. Acommunication device according to claim 13, wherein a data discriminator(32′) determining the type of received data is connected to thereceiving electronics (37), to which different data processing circuits(49, 51) are connected to which the respective data are supplied independence on the data type determination.
 21. A communication deviceaccording to claim 13, wherein a memory (53) for predetermined messagesis associated to a data processing circuit (51) and in that datatransmitted in the second direction (14) from a different motor vehiclecommunication device, received via the IR receiving elements (9) andsupplied by the receiving electronics (37) to the data processingcircuit (51) comprise address information for reading out the respectivemessages from the memory (53).
 22. A communication device according toclaim 21, comprising an optic and/or acoustic reproduction unit (52) forthe messages.
 23. A communication device according to claim 13, whereina data processing circuit (49) is associated to a fee charging unit (50)as well as connected to the transmission electronics (36.1) forreturning data relating to fees charged in the second direction (14).